For my final project, I chose to revisit the Valley of Oaxaca dataset from a previous module assignment. I used the soil and site data from the grids N6E4, N6E5, and N6E6 to test a hypothesis concerning the rise of the Zapotec state. If population pressure was exceeding the regional carrying capacity, we would expect to see phases where the population is much greater than could be supported by agricultural yield estimates in their catchment circles. I completed this analysis with the help of ArcGIS products. Here is a basic outline of steps I created for myself to help with the analysis process.
Methods:
1) Determine time periods to use and make into separate layers.
- 4 time periods total
2) Buffer the sites with a 2 kilometer radius with the Buffer tool.
- Make sure buffers are set to dissolve all.
- 4 buffer outputs total
3) Convert the site polygons into point features using the Feature to Point tool.
- 4 site point feature outputs total
4) Use the site points to create Thiessan Polygons for each time period.
- 3 Thiessan Polygons total
5) Combine the site buffers with the Thiessan Polygon outputs using the Intersect tool.
- 3 intersects total
6) Edit the intersect outputs, snapping the edges of the Thiessan polygon to the buffer and grid boundaries.
- 3 edits total
7) Clip the soil type to the newly edited intersect outputs with the Clip tool.
- 9 clips total
8) Calculate area in hectares of soil clips using the Calculate Geometries function.
9) Perform a spatial join between the clip layers and point file data.
- This combines the population data with the land area data.
Based on these results, I was able to determine if the population
of each site could subsist on the amount of hectares available within their 2
km catchment radius. One adult human can subsist on a
minimum of .5 ha of arable land. For ease of results, 1 ha will equate to
feeding 1 human
The Early I phase
settlement had an estimated population of 185, with 220 ha of Type I land and
1507 ha of Type III all arable land at their disposal. They would require 185
to 370 ha at most in order to sustain their population. Based on the amount of
each land type available to them, they should have been able to support their
population on Type I and Type III all arable land.
The Late I phase has an estimated population of
941, with only 220 ha of Type I land available, 415 ha of Type III 10% arable,
and 1834 ha of Type III all arable land. They would require 941 to 1882
hectares of land at most in order to sustain their population. In terms of yield
productivity, they would not have enough Type I or Type III 10% arable land to
sustain their population. There would be enough Type III all arable land, but
productivity and yields would not be as reliable as Type I land.
The Monte Alban II phase had an estimated
population of 774, with only 220 ha of Type I land and 1579 ha of Type III all
arable land available to them. They would require 774 to 1548 hectares at most
in order to sustain their population. They would not have been able to produce
enough yields with Type I land. They barely meet the requirements for
subsistence on Type III all arable land, which was established as not having
reliable yields.
